Sorry for the delay in getting back to you, haven't had the time for a longer post this week just a few short ones.
I agree with you that my use of heel lifts doesn't fit with conventional theory or really logical thinking on the subject. When I think about it the fact that I can have someone do the squat test, measure how much I have to raise the heel of the boot for them to get all the way down then put that much lift inside the boot and they are then able to preform the full squat it just doesn't make sense. My mind tells me that the two different ways of raising the heel, one which changes forward lean one which has no effect on forward lean, should produce different results but they don't. Let me throw out another idea that I've toyed with.
All this toying with ramp angle has no direct effect what so ever on the position of the CM. At rest we want to position our CM over a small area between out feet and somewhere about two thirds back along the length of our feet, for ease in writing this I'm going to call this our balance point. If we move the CM to far in front of this balance point then we start to fall forward and must start walking. If I force my ankle to have a set bend in it that differs from its natural resting flex position (which we do with ski boots) then my other joints (knee, hip, spine) have to flex in ways to compensate for this and keep the CM over the balance point. When I raise or lower the heel of a subject I affect this point moving it either toward the toes or toward the heel. When this happens the body must make adjustments to keep the CM over this relocated balance point. I know this must sound way out there to you (it does to me) but it does explain what I observe and that is what I am trying to do.
One of the comments in the letter that HH wrote that was posted by SCSA ties in with this I think. It was about a relationship between the center of hip position and the line defined by the midpoint of the boot sole. I think that this may be the point which defines the farthest forward point which we can move the CM over before we must move the feet forward to keep from falling. Let me talk my way through this and see if it makes any sense.
I have a resting balance point which I position my CM over and I can maintain this position with no muscular effort. I can move my CM forward of this point and stay at rest, because of the structure of my feet, but I must use muscular effort to maintain this position. There is a limit to how far forward I can move the CM before the whole system tips over and no amount of muscular effort will prevent this. Again for ease in thinking about this and writing about it I am going to call this the movement point. There is a small distance between the balance point and the movement point, probably measured in mms. For the sake of argument let's consider the movement point fixed. Raising the heel moves the resting balance point forward (you referred to a heel lift making you feel balanced more forward) closer to the movement point. This means that it requires less movement of the CM to produce forward movement. It is easier to move forward which is one of the prime requirements of skiing.
This would mean that what I am doing when I "align someone in the fore/aft plane" is to bring the resting balance point and the movement balance point closer together so that the subject can move forward with a minimum of deviation from their "natural athletic stance".
Does any of the above make any sense to you?
By the way, I do allow for the ramp angle of the binding when I do the squat test by placing a spacer under the heel to raise it as much as the ramp of the binding does. I have also found that the squat test is a very accurate method of determining how much adjustment in ramp a subject needs. It somehow takes into account all the variables involved in this complicated subject and gives me a measurement I can use as a "fix". And once I make this "fix" I find that further adjustments (based on on-hill feedback) are minimal. It even predicted that I would need a 4cm (yes that's cm) plus adjustment and guess what, it worked. By the way this is the kind of ramp used to allow someone with fused ankles to ski and while my ankle flex may be slightly less than normal they are by no means fused. Something else caused my extreme fore/aft mis-alignment but the ramp, most of it in the boot, has solved the problem.
Your idea about the four scales is very intriguing and if I can find and afford scales that are suitable for setting up such a contraption I may set one up in my shop just to see the data that it can produce.
Anyway I've produced another long post so I'll end here with my usual thanks for keeping my mind from becoming fuzzy, or helping it become fuzzy, I'm not always sure which is happening sometimes.